1. Field of the Invention
The present invention relates to an image forming apparatus, a power supply control method, and a power supply control program, and more particularly to an image forming apparatus including a fixing apparatus provided with a heating member, such as a fixing heater that heats with charging power of a capacitor, an power supply control method and a power supply control program which use the image forming apparatus.
2. Description of the Related Art
A heating member (fixing heater) in a fixing apparatus used for an image forming apparatus, such as an electrophotographic type image forming apparatus preferably requires a rapid supply of electric power. In addition to a power supply from a commercial power source, a chargeable subsidiary power source using an electric double layer condenser, for example, is applied to a heating member of a fixing apparatus used for an electrophotographic type image forming apparatus, as disclosed in Japanese Laid-Open Patent Application Nos. 2000-315567, 2002-357966, and 2003-140484, for providing a technology enabling rapid build up and enhancing energy conservation ability.
With the technology disclosed in the above-described documents, deterioration of fixation property caused by lack of electric power can be prevented since the technology uses a large size capacitor as an subsidiary power source for enabling instantaneous supply of large current to a fixing apparatus in a case where the power supply from a commercial power source to the fixing apparatus is short. The foregoing technology, however, requires the capacitor to be charged at certain timing after the power is supplied to the heating member by the discharge of the capacitor.
That is, with this type of image forming apparatus, the capacitor is to be charged by supplying power from the commercial power source to a charging circuit during a waiting time which is a time other than an image forming operation (includes, for example, standby mode, energy save mode). Meanwhile, even during the waiting time, the temperature of a fixing roller is to be maintained at a substantially uniform temperature by the heating member, such as an AC halogen heater which heats by receiving power supply from the commercial power source.
For example, in a case where plural AC halogen heaters are employed in correspondence with, for example, the sizes of paper, the AC halogen heaters inside a fixing roller may be configured in a manner shown in FIG. 15. FIG. 15 is a drawing showing an exemplary configuration of AC halogen heaters provided in the fixing roller. In a case of forming an image on an A4 size paper, only an AC halogen heater 1000, being disposed at the center of FIG. 15, is used. In a case of forming an image on a wide size paper, such as A3 size paper, the AC halogen heater 1000 in the center and AC halogen heaters 1001 and 1002 disposed on both sides thereof are used simultaneously.
Furthermore, in a case where the power of the AC halogen heater 1000 is 600 W (=P1), the power of the AC halogen heaters 1001 and 1002 are 700 W (=P2), the power for charging the capacitor is set to, for example, 500 W (=P3) so as to satisfy a relation of “P1, P2>P3”.
In a case of lighting the AC halogen heaters 1000, 1001, and 1002 at the same time of charging the capacitor due to the fall of temperature of the fixing roller during a waiting time, the power for charging the capacitor would exceed a power being no less than a rated power (for example, in Japan, the rated power of a typical plug socket is no less than 15 A/1500 W). Accordingly, a charging circuit, serving to charge the capacitor, is designed for restraining the charging power to a power no more than the rated power in a case where the power P1 of the AC halogen heater 1000 and the power P3 for charging the capacitor are simultaneously used, or a case where the power P2 of the AC halogen heaters 1001 and 1002 are used and the power P3 for charging the capacitor are simultaneously used.
Furthermore, in the above-described conventional example, the temperature of the AC halogen heater 1000 is optimally controlled in accordance with the detection value obtained from a thermistor 1010, and the temperatures of the AC halogen heaters 1001 and 1002 are optimally controlled in accordance with the detection values obtained from thermistors 1011 and 1012.
Nevertheless, in a case of separately controlling the temperature of the AC halogen heater 1000 and the temperatures of the AC halogen heaters 1001 and 1002, there is a possibility that the AC halogen heaters 1000, 1001, and 1002 are lighted at the same time, thereby leading to a risk of charging the capacitor to a power same as or greater than the rated power. When the power is same as or greater than the rated power, the image forming apparatus is unable to use the commercial power source.
It is to be noted that the length of charging time would extend if the power to the capacitor is restrained to a power which is same as or less than the rated power. Therefore, in a case where a user commands an image forming operation in the midst of charging the capacitor, image forming performance may deteriorate due to lack of charge of the capacitor.